Generators that are driven by an internal combustion engine are known per se. The internal combustion engine may be coupled to an electric generator and a frequency converter may be connected downstream of the generator.
U.S. Patent Publication No. 2009/0194067 A discloses a mobile system having a network-independent energy source in the form of an internal combustion engine and individual assemblies driven by the internal combustion engine, including a generator provided as a current/voltage source. The energy provided by the internal combustion engine and the energy needed by the or each assembly are monitored. If the energy needed exceeds the available energy, a rotational speed target value that is used to control the rotational speed of the internal combustion engine is increased or individual assemblies are deactivated according to a priority scheme, so that either the available energy is increased or the energy requirement is reduced.
DE 10 2004 017 087 A1 discloses an assembly with an internal combustion engine. The assembly having an internal combustion engine is used as a drive source, which is rotationally connected to an energy generator, (e.g., an electrical generator, a hydraulic pump, an air compressor or the like). The internal combustion engine has a rotational speed controller for stabilizing a preselected rotational speed, wherein the rotational speed controller controls a control member of the internal combustion engine in order to vary the amount of fuel supplied to the internal combustion engine up to a full load limit. The assembly also has a unit for measuring the change in load of the energy generator, wherein the unit is operatively connected to the rotational speed controller of the internal combustion engine by a signal link in such a manner that the control member of the internal combustion engine may be actuated by the unit independently of the rotational speed controller.
The trend for arrangements having a generator coupled to an internal combustion engine is moving towards lightweight construction, and therefore, for example, balance weights, as have previously been provided to compensate any fluctuations in rotational speed, are if possible avoided or at least the moved masses are reduced. The generator may be operated at a predefined or predefinable rotational speed. For this purpose, the generator is assigned a rotational speed controller. The internal combustion engine and the combustion process taking place therein are managed by controlling the rotational speed. This may be done according to different criteria. For example, power, efficiency, and emission are conceivable.
Previously, the balance weight on the generator has been increased in order to obtain greater rotational speed stability of the generator. However, such an increase in the moved masses is actually undesirable, especially if the internal combustion engine and the generator are part of a motor vehicle or the like and are moved together from the motor vehicle. As an alternative, the rotational speed control was previously accordingly operated with maximum dynamics in order to achieve a broad range and high closed-loop gains. A possibility in this regard includes the use of very high clock frequencies of the rotational speed controller. However, this may result in excessively increased power losses in the switching elements.